Fixes/amend 9825f7f + amend Changelog (#4857, #5937)

docs/CHANGELOG.txt

@@ -42,6 +42,7 @@ Other changes:
 - Fixed cases where CTRL+Tab or Modal can occasionally lead to the creation of ImDrawCmd with
   zero triangles, which would makes the render loop of some backends assert (e.g. Metal with
   debugging, Allegro). (#4857, #5937)
+- Tables, Columns: Fixed cases where empty columns may lead to empty ImDrawCmd. (#4857, #5937)
 - Inputs, Scrolling: better selection of scrolling window when hovering nested windows
   and when backend/OS is emitting dual-axis wheeling inputs (typically touch pads on macOS).
   We now select a primary axis based on recent events, and select a target window based on it.

imgui_draw.cpp

@@ -447,10 +447,13 @@ void ImDrawList::AddDrawCmd()
 // Note that this leaves the ImDrawList in a state unfit for further commands, as most code assume that CmdBuffer.Size > 0 && CmdBuffer.back().UserCallback == NULL
 void ImDrawList::_PopUnusedDrawCmd()
 {
-    if (CmdBuffer.Size == 0)
+    while (CmdBuffer.Size > 0)
-        return;
+    {
-    for (ImDrawCmd* curr_cmd = &CmdBuffer.Data[CmdBuffer.Size - 1]; curr_cmd->ElemCount == 0 && curr_cmd->UserCallback == NULL; curr_cmd--)
+        ImDrawCmd* curr_cmd = &CmdBuffer.Data[CmdBuffer.Size - 1];
+        if (curr_cmd->ElemCount != 0 || curr_cmd->UserCallback != NULL)
+            return;// break;
         CmdBuffer.pop_back();
+    }
 }
 
 void ImDrawList::AddCallback(ImDrawCallback callback, void* callback_data)